In hand display type electronic watches which display time using hands, many multifunctional watches using a plurality of motors and possessing various functions as well as a time display function are conventionally manufactured as commercial products. Such a multifunctional watch is at present indispensable as one type of wrist watches. However, the wrist watch must have excellent portability and be compact, light, and inexpensive. Therefore, there is a certain limitation to the multifunctional provision of using a certain motor for a certain functional display.
There is a known structure disclosed in Japanese Patent Publication No. 41071/1976 for driving, each time as required, a date plate for displaying the date, which is one of the functions.
Japanese Patent Publication No. 41071/1976 discloses a structure in which, in the case of date feed only, the standard drive of constantly rotating hour and minute train wheels and the like is switched to a geneva system to drive the date plate and thereby achieve efficiently such a function as that of a date plate which is driven once a day.
In such a structure for driving the date plate in connection with motors for driving hour, minute, and second hands, however, a complex structure is required to convert the momentum for turning seconds equivalent to one day into the momentum for advancing the date by one day. This is unsuitable for the specifications of the watch. Therefore, the date plate is usually isolated from the motors for driving hour, minute, and second hands and is driven by a separate forced driving means.
A method in which the date plate is driven by an independent motor is a simple method for promoting multifunctionalization. This method requires a motor and train wheels used exclusively for the date plate, which causes further circuit complexity and increases the number of parts. Therefore, it is difficult to assemble a watch in a limited space giving rise to the problem wherein the watch is large or thick.
It is an object of the present invention to provide a functional display unit which can display many functions using a reduced number of motors thereby enabling a multifunctional display without making the electronic device large or thick, in small electronic apparatus such as timepieces possessing a plurality of display functions.